The present invention relates to ophthalmic surgical devices and methods. More particularly, the present invention relates to a novel plunger device and method for inserting an intraocular lens (hereinafter “IOL”) into an eye.
IOLs are artificial lenses used to replace the natural crystalline lens of the eye when the natural lens has cataracts or is otherwise diseased. IOLs are also sometimes implanted into an eye to correct refractive errors of the eye in which case the natural lens may remain in the eye together with the implanted IOL. The IOL may be placed in either the posterior chamber or anterior chamber of the eye. IOLs come in a variety of configurations and materials. Some common IOL styles include the so-called open-looped haptics which include the three-piece type having an optic and two haptics attached to and extending from the optic; the one-piece type wherein the optic and haptics are integrally formed (e.g., by machining the optic and haptics together from a single block of material); and also the closed looped haptic IOLs. Yet a further style of IOL is called the plate haptic type wherein the haptics are configured as a flat plate extending from opposite sides of the optic. The IOL may be made from a variety of materials or combination of materials such as PMMA, silicone, hydrogels and silicone hydrogels, etc.
Various instruments and methods for implanting the IOL in the eye are known. In one method, the surgeon simply uses surgical forceps having opposing blades which are used to grasp the IOL and insert it through the incision into the eye. While this method is still practiced today, more and more surgeons are using more sophisticated IOL injector devices which offer advantages such as affording the surgeon more control when inserting the IOL into the eye. IOL injector devices have recently been developed with reduced diameter insertion tips which allow for a much smaller incision to be made in the cornea than is possible using forceps alone. Smaller incision sizes (e.g., less than about 3 mm) are preferred over larger incisions (e.g., about 3.2 to 5+ mm) since smaller incisions have been attributed to reduced post-surgical healing time and complications such as induced astigmatism.
Since IOLs are very small and delicate articles of manufacture, great care must be taken in their handling. In order for the IOL to fit through the smaller incisions, they need to be folded and/or compressed prior to entering the eye wherein they will assume their original unfolded/uncompressed shape. The IOL injector device must therefore be designed in such a way as to permit the easy passage of the compressed IOL through the device and into the eye, yet at the same time not damage the delicate IOL in any way. Should the IOL be damaged during delivery into the eye, the surgeon will most likely need to extract the damaged IOL from the eye and replace it with a new IOL, a highly undesirable surgical outcome.
IOL injector devices typically incorporate a plunger that telescopes within a tubular injector body. As the plunger is advanced within the injector body, the distal plunger tip pushes the IOL through the injector body with the IOL ultimately exiting the device at the narrow open tip of the injector device. The surgeon positions the narrow open tip into the incision made in the eye to express the IOL from the injector open tip into the eye. The plunger tip is therefore a critical design component of the injector device in that it creates the force necessary to advance the IOL through the injector device. In most, if not all, of the injector devices on the market today, the injector tip makes direct contact with the IOL. It will be appreciated that direct contact of the IOL with any injector components increases the risk of damage to the IOL. Damage to IOL during delivery is many times attributable to the plunger tip which may inadvertently scratch or tear the IOL as it engages and advances the IOL through the injector device. The chance of IOL damage is heightened during the latter part of the IOL advancement stage where it is being compressed and pushed through the narrowing inserter passage at the same time. This is because the force required to push the IOL through the inserter device necessarily increases as the IOL is being compressed through the ever-narrowing injector lumen. This latter stage of IOL advancement is therefore a critical stage where forces upon the IOL are at their greatest and the IOL is more susceptible to damage caused by those forces.
There therefore remains a need for an injector device which will advance and expel the IOL from the injector open tip and into the eye in a non-destructive and controlled manner.